How to 4K video output from HDMI

[tomo]

I have an i.MX 8MQ EVK and now evaluating.

I'm trying to output 4K video via HDMI port, but it does not work.

I was download 'L4.9.88_2.0.0_mfg-tool_MX8MQ.tar.gz' from NXP website and make a SD card for boot that using a script 'mfgtool2-yocto-mx8-evk-sd2.vbs' with Mfgtool2.

After making, boot from SD card.
Default is displaied by 1080p60 from HDMI port and it works.

I refered some post and changed bootargs setting to 4K output, but not works.

Getting an HDMI output on IMX8QMLPDDR4ARM2 

Monitor not working for MCIMX8M-EVK 

Getting a 4K HDMI output on MCIMX8M-EVK 

Is it correct procedure?
Or the OS does not support 4K yet?
I'll attached boot log.

Best regards,
tomo

[joanxie]

when you use the command as log file, nothing shows up, right? how about 4K @30? any different? when the board boot up,  try to use "cat /sys/class/graphsics/fb0/mode", what's result do you get?

[tomo]

Thank you for your reply.

I can see the Linux desktop by 1080p when even at 4K setting.
I tried '3840x2180-32@60', '3840x2180-32@30', '3840x2180-32@25', but result was same.
I think it may be ignoring 4K setting because pixclk will overrange.
(You can see below messages in log file.)

-----

[ 1.140399] [drm] Pixel clock frequency: 712254 kHz, character clock frequency: 712254, color depth is 8-bit.
[ 1.140413] [drm:phy_cfg_t28hpc] *ERROR* This pixel clock frequency (712254 kHz) is not supported.
[ 1.140420] [drm:hdmi_phy_init_t28hpc] *ERROR* failed to set phy pclock
[ 1.140427] [drm:imx_hdp_bridge_mode_set] *ERROR* Failed to initialise HDP PHY

-----

I checked below path.
root@imx8mqevk:/sys/class/graphics/fb0# cat mode
root@imx8mqevk:/sys/class/graphics/fb0# cat modes
U:3840x2160p-0

/sys/class/graphics/fb0/mode was displayed nothing.

Best regards,

tomo

[joanxie]

refer to your cat command, you get U:3840x2160p-0, which means your output 4K successfully,  could you upload the log file

[tomo]

I don't have a 4k monitor now, so I will recheck that if the monitor is returned.

Thank you.

tomo

[lingguan]

Hello, do you find the reasons?